1. Field of the Invention
The present invention relates to a laminated iron core and a manufacturing method, of a laminated iron core. In particular, the present invention relates to a laminated iron core and a manufacturing method of a laminated iron core in which when the laminated iron core is manufactured by using multiple iron core pieces taken from a steel plate, sources of the iron core pieces are easily recognized, when the iron core pieces are turned and laminated to manufacture the laminated iron core, a turned, and laminated state of the iron core pieces is easily recognized, or when the iron core pieces are skewed to manufacture the laminated iron core, the skew is easily recognized.
2. Description of the Related Art
The laminated iron core forming an electric motor or a generator is manufactured in such a way that iron core pieces blanked or stamped out from a steel plate are laminated. At that time, in order to improve a productivity or a yield, a blanking die unit layout may he sometimes used that a plurality of iron core pieces are blanked out and formed from one steel plate at the same time (namely, the multiple iron core pieces are taken). When the multiple iron core pieces are taken from the steel plate, which row where the iron core piece forming the laminated iron core is blanked needs to be identified (Namely, the source of the iron core piece is recognized) in order to recognize the quality of the manufactured laminated iron core. Accordingly, in each row that the iron core is blanked or stamped out, a part of a configuration of the iron core piece is changed (for instance, small irregularities or cut-out parts are provided in a part of an outer peripheral part or an inner peripheral part of the iron core piece) to identify which row where the iron core piece is blanked out. For instance, two rows of the iron core pieces are taken from the steel plate, as shown in FIGS. 9A and 9B, in one iron core piece 80 which is blanked out from the one row, one recessed part 82 is formed in an edge part of one through hole 81 of a plurality of through holes formed for cooling. In an iron core piece 83 which is blanked out from the other row, two recessed parts 82 are formed in an edge part of one through hole 84 of a plurality of through holes. FIGS. 9A and 9B also show a shaft hole 85 and a magnet-insert hole 86.
For the purpose of improving a property of the laminated iron core, in an inner part of a blanking die unit or in an outer part of the blanking die unit, the blanked iron core pieces may be sometimes turned, and laminated or the iron core pieces may be turned and laminated while skewing. In this case, the turned and laminated state of the iron core pieces or whether or not the skew is assuredly applied to the iron core pieces to laminate the iron core pieces needs to be recognized. At that time, when a configuration of the iron core piece is symmetrical in rotation, a recognition work cannot be done by a method of an examination of an external appearance of the laminated iron core. For instance, JP-U-64-9437 as Patent Literature 1 discloses that a quantity of skew detecting remark is provided in one or a plurality of positions in an outer peripheral part of the iron core piece (namely, a part of the configuration of the iron core piece is changed).
Patent Literature 1: JP-U-64-9437